A system and method are provided for automatic fitting of all audio signals according to the ear in which a user is using to receive audio signals from a host device. The host device incorporates an audio signal fitting device, which may comprise an inquirer configured to query the host device for an in-use audio producing transducer; an electronic mechanism configured to identify an ear which a user is using to receive audio signals from a host device, based on the in-use audio producing transducer; and a notifier configured to instruct the host device, based on the identified ear, to output a channel of audio signals to the in-use audio producing transducer. The ear in use may be deduced from inertial data. The instructions may specify a particular channel of audio signals, or enhancement thereof to adjust for characteristics of the identified ear, for example by applying frequency-specific gain adjustments to adjust for frequency response characteristics of the identified ear, and/or to adjust for a detected or typical signal pathway used to transmit a signal to the identified ear.